I was recently forwarded an internal email where a ‘thought leader’ at a scientific institution called the hope that we wouldn’t all become infected with COVID-19 naïve and suggested reopening the economy sooner rather than later so that we’d start to build herd immunity.

I’m also hearing the term herd immunity coming out of the mouths of politicians worldwide—usually, again, in the context of the economy.

It’s time to do the damn math. Are most of us really going to get COVID-19? Or can we deliberately expose/infect enough younger healthier workers so we can restart the economy and have herd immunity work to protect the most vulnerable against this disease?

Herd immunity happens when there are enough people within a society who are immune to an infectious disease so that it can no longer spread efficiently. 100% of people don’t need to have been infected/immune for herd immunity to happen. Depending on how contagious a pathogen is, once a population hits 60-80% immunity, herd immunity will begin to protect all members of society, and will decrease disease spread. The more contagious a disease is, the more people must be immune to it for herd immunity to start to protect even those who were never infected themselves. Here’s my diagram of this:

OK, so herd immunity sounds pretty good, right? It works pretty well for other diseases, helps limit spread of the flu, and herd immunity even protects the poor children of idiots who choose not to allow them to get safe and effective vaccines against dangerous pathogens like measles (even though unvaccinated individuals themselves are not immune). Because COVID-19 is so contagious, ~80% of the members of society will need to have survived COVID-19 before herd immunity will significantly protect us. What will it take for 80% of us to have infected/recovered from COVID-19?

Let’s do the math. We’ll use the numbers coming out of New York City for this example. As of 4/16/20, there have been over 120,000 confirmed cases* in this outbreak epicenter. Over 12,000 deaths. That’s a lot.

But in a city of 8.7 million, 120,000 is only 1.4% of the population.

Only 1.4% of the population is confirmed ill with COVID-19, and hospitals look like war zones.

1.4%, and mass burials are happening.

1.4%, and refrigerated trucks are humming on the city streets where they’ve been used for weeks as morgues.

1.4%, and medical caregivers are experiencing unprecedented levels of burnout—and sometimes becoming infected themselves and, in far too many cases, dying.

1.4%, and NYC area hospitals are completely overwhelmed with COVID, jeopardizing patients with other healthcare needs.

1.4%, and the economic heart of America has stopped beating.

This is what it looks like when less than 2% of the population of a single American city becomes infected with COVID-19.

Can you imagine what it would take for 80% of the population to become infected with COVID-19 across the USA**?

Even if the human costs are acceptable to the powers that be, how long would it take to manage the slow burn necessary to keep the infection rate to a level our healthcare and funeral systems can cope with?

I hope our ‘thought leaders’ and politicians do the damn math sooner rather than later. To me, the numbers are screaming that planning on any degree of herd immunity to COVID-19 is the ‘naive hope’.

We simply can’t succumb to COVID-19. We have to work together to continue to beat back this disease through continued social distancing, aggressive diagnosis, improved treatments, and, ultimately, hopefully, vaccinations– which represent our only true hope for herd immunity.

It’s gonna hurt, economically. But we just have no other options yet against the living nightmare that is COVID-19.

* It’s true that confirmed cases underestimate the number of actual cases, due to lack of testing and/or false negative tests. Until a reliable antibody test is developed, we won’t know, and so I’m using the best data available. However, NY leads the country in testing, and even doubling the number of confirmed cases means that only about 3% of NYC residents have been infected, resulting in the catastrophic reality described above.

 

**For now, I’m not factoring in reports that some people seem to get reinfected with COVID-19—for this discussion, let’s say that once you’ve had COVID-19, you can’t get it again.